Defect passivation in hybrid perovskite solar cells using quaternary ammonium halide anions and cations

Meng

Advanced Energy Materials

2017

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374

265

Organic‐inorganic halide perovskite materials have become a shining star in the photovoltaic field due to their unique properties, such as high absorption coefficient, optimal bandgap, and high defect tolerance, which also lead to the breathtaking increase in power conversion efficiency from 3.8% to over 22% in just seven years. Although the highest efficiency was obtained from the TiO2 mesoporous structure, there are increasing studies focusing on the planar structure device due to its processibility for large‐scale production. In particular, the planar p‐i‐n structure has attracted increasing attention on account of its tremendous advantages in, among other things, eliminating hysteresis alongside a competitive certified efficiency of over 20%. Crucial for the device performance enhancement has been the interface engineering for the past few years, especially for such planar p‐i‐n devices. The interface engineering aims to optimize device properties, such as charge transfer, defect passivation, band alignment, etc. Herein, recent progress on the interface engineering of planar p‐i‐n structure devices is reviewed. This review is mainly focused on the interface design between each layer in p‐i‐n structure devices, as well as grain boundaries, which are the interfaces between polycrystalline perovskite domains. Promising research directions are also suggested for further improvements.

Section: The Perovskite/etm Interfacementioning

confidence: 99%

Interface Engineering for Highly Efficient and Stable Planar p‐i‐n Perovskite Solar Cells

Meng

Advanced Energy Materials

2017

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374

265

“…Developing low-temperature-processed electron-transport layer (ETL) [8] for planar structure devices is of great importance. [15] Therefore, sufficient charge extraction is one of the most important contributors for device efficiency. [14] The insufficient charge extraction between perovskite and ETL can result in charge accumulation, which negatively affects device performance.…”

mentioning

confidence: 98%

“…[14] The insufficient charge extraction between perovskite and ETL can result in charge accumulation, which negatively affects device performance. [15] Therefore, sufficient charge extraction is one of the most important contributors for device efficiency. [16] Recently, researchers have focused on the use of bilayer ETL, [17] and the bilayer stack structure has been demonstrated to be effective for improving device efficiency.…”

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confidence: 98%

Gradient Energy Alignment Engineering for Planar Perovskite Solar Cells with Efficiency Over 23%

et al. 2020

Organic-inorganic halide perovskite solar cells (PSCs) have a great potential for commercialization owing to their low cost and superior performance. [1] Over the past decade, the power conversion efficiency (PCE) of PSCs has increased from 3.8% [2] to 25.2%, [3] approaching the record efficiency of 26.7% of crystalline silicon solar cells, [4] and becoming one of the most promising candidates for the nextgeneration efficient and low-cost photovoltaic devices. [5] For example, Seok and co-workers introduced additional iodide intoprecursor solutions, resulting in a certified PCE of 22.1%. [6] Recently, Kim et al. investigated the effects of methylammonium chloride (MACl) on the performance of perovskite films and fabricated a device that achieved a certified PCE of 23.5%. [7] It is important to note that all these efficient devices were fabricated with high-temperature-processed TiO 2 mesoporous structures, thus limiting their widespread application. Developing low-temperature-processed electron-transport layer (ETL) [8] for planar structure devices is of great importance. [9] Among them, TiO 2 , [10] SnO 2 , [11] and [6]-phenyl-C 61 -butyric acid methyl ester (PCBM) [12] are the most commonly used ones.The lower efficiency of devices based on planar structures is closely related to insufficient charge extraction [13] and imperfect interfacial band alignment. [14] The insufficient charge extraction between perovskite and ETL can result in charge accumulation, which negatively affects device performance. [15] Therefore, sufficient charge extraction is one of the most important contributors for device efficiency. [16] Recently, researchers have focused on the use of bilayer ETL, [17] and the bilayer stack structure has been demonstrated to be effective for improving device efficiency. As early as 2014, [18] Snaith and co-workers have shown that PSCs with C 60 -modified TiO 2 can significantly enhance electron transfer and result in a largely improved performance of 17.3% and a decrease in hysteretic behavior. Petrozza and co-workers demonstrated that insufficient charge extraction from the perovskite film to the ETL can be remedied using a TiO 2 /PCBM bilayer ETL, and a PCE of 17.9% was achieved. [19] Recently, Choi and co-workers achieved a PCE of 21.1% using SnO 2 @TiO 2 ETL, [20] and Kong and co-workers showed a PCE of 21.4% using the same type of ETL. [21] Numerous other efforts have been undertaken to enhance the performance of PSCs with bilayer ETLs, such as SnO 2 @TiO 2 , [22] SnO 2 /PCBM, [23] An electron-transport layer (ETL) with appropriate energy alignment and enhanced charge transfer is critical for perovskite solar cells (PSCs). However, interfacial energy level mismatch limits the electrical performance of PSCs, particularly the open-circuit voltage (V OC ). Herein, a simple low-temperature-processed In 2 O 3 /SnO 2 bilayer ETL is developed and used for fabricating a new PSC device. The presence of In 2 O 3 results in uniform, compact, and low-trap-density perovskite films. Moreover, the conduction...

“…the efficiencies (from 19.2 up to 21.0%) was to passivate ionic defects at the top surface of the perovskite by choline chloride. With this, the density of states was severely reduced over the whole trap depth region [52]. In the case of n-i-p solar cells, the group of Ted Sargent in Toronto used a chlorine-capped TiO2 layer (au lieu of typical TiO2) as the crystallization substrate, passivating traps and reducing recombination at the interface which forms upon contact of the n-type layer with the Cs0.05FA0.81MA0.14PbI2.55Br0.45 perovskite.…”

Section: Mixed Perovskites In N-i-p and P-i-n Solar Cells: Is The Excmentioning

confidence: 99%

Anti-Solvent Crystallization Strategies for Highly Efficient Perovskite Solar Cells

et al. 2017

Solution-processed organic-inorganic halide perovskites are currently established as the hottest area of interest in the world of photovoltaics, ensuring low manufacturing cost and high conversion efficiencies. Even though various fabrication/deposition approaches and device architectures have been tested, researchers quickly realized that the key for the excellent solar cell operation was the quality of the crystallization of the perovskite film, employed to assure efficient photogeneration of carriers, charge separation and transport of the separated carriers at the contacts. One of the most typical methods in chemistry to crystallize a material is anti-solvent precipitation. Indeed, this classical precipitation method worked really well for the growth of single crystals of perovskite. Fortunately, the method was also effective for the preparation of perovskite films by adopting an anti-solvent dripping technique during spin-coating the perovskite precursor solution on the substrate. With this, polycrystalline perovskite films with pure and stable crystal phases accompanied with excellent surface coverage were prepared, leading to highly reproducible efficiencies close to 22%. In this review, we discuss recent results on highly efficient solar cells, obtained by the anti-solvent dripping method, always in the presence of Lewis base adducts of lead(II) iodide. We present all the anti-solvents that can be used and what is the impact of them on device efficiencies. Finally, we analyze the critical challenges that currently limit the efficacy/reproducibility of this crystallization method and propose prospects for future directions.